Rotary duplicating apparatus



April 28, 1959 w. EICHENBAUM ET AL. 2,883,929

' ROTARY DUPLICATING APPARATUS Filed Nov. 10, 1953 2 Sheets-Sheet 1 IN VEN TOR.

A-r-ro QNbr United States Patent ROTARY DUPLICATING APPARATUS William Eichenbaum, Jersey City, NJ and Manley Mandel, Amherst, Mass.

Application November 10, 1953, Serial No. 391,199 11 Claims. or. 101-1325 Innumerable business establishments, especially those engaged in finance and installment selling operations, have a pressing need for a speedy and economical system for preparing and repeatedly handling mass mailings. Although the use of conventional addressograph equipment is functionally suitable, it is often unfeasible to use this equipment due to the initial installation cost, as well as the continuous expense of preparing metallic addres sograph plates. where anywhere from a fewto. several hundred mailings are needed'for a single addressee. This range is usually too small to merit the relatively large cost of the addressograph equipment, yet too large for individual typing without prohibitive expense. In .an attempt to meet these problems, further systems have been devised using masters of stencil paper supported within relatively thick and rigid frames. These-systems likewise present difficulties, especially from the standpoint of the initial cost, and the difiiculties encountered in preparing and handling the masters.

It has been found that optimum results are obtainable with relatively flexible paper master cards having hecto graph impressions which may be prepared, handled and stored speedily and conveniently, the initial preparation requiring only the conventional equipment needed for typing hectographs.

Accordingly, it is an object of the present invention to provide a new and improved duplicating machine for successively bringing paper-stock masters having hectographed impressions into transfer relation to impressionreceiving blanks. Although the invention is especially advantageous in mass mailings with masters having hecto graph impressions, it is to be expressly understood that the applications are virtually coextensive with the known uses of duplicating and addressograph machines.

Duplicating equipment conventionally employs printing rollers or platens which are intermittently fed with successive masters and impression-receiving blanks to be brought into transfer relation. Although it is generally possible to automatically deliver the prepared masters and blanks to the printing rollers substantially at the same feed rate, experience has indicated that conventional feeder means preclude high speed operation with the required degree of reliability. In this respect, it is not uncommon for a feeder to skip, resulting in the failure to deliver a master or blank for the impression-transfer operation. This tendency becomes more pronounced, when handling bendable stock, such as flexible paper masters.

Accordingly, it is a further object of the present invention to provide addressograph equipment designed for Frequently, the situation arises 2 high-speed handlingof masters and blanks, with minimum risk of faulty operation as by skipping in delivery of masters and/or blanks. It is within the contemplation of the invention to provide a positive control and check which assures tandem delivery of prepared masters and blanks to the printing rollers of duplicating equipment.

Certain objects of the invention are realized by the provision of coincidence-detecting means which are effective to preclude delivery of unpaired blanks and masters to the printing rollers. In accordance with a pre ferred embodiment of the invention, roller-type duplicating equipment is provided having separate feed paths arranged to deliver masters and impression-receiving blanks to the printing or reproducing rollers. Sensing means are arranged at selected locations along the separate feed paths for determining coincidence of a master and a blank prior to advance of a coinciding pair for the printing operation. The sensing means in turn con! trol appropriate mechanisms which, after sensing pairing, permit delivery of successive paired masters and blanks to the reproducing rollers.

' As a further feature of the invention, individually con, trollable feeders are provided for the separate delivery paths, which are rendered inoperative While successive pairings are checked. This avoids backup of the masters and impression-receiving blanks along the individual feed paths and the incident risk of fouling the feeders.

The above and still further o je features and ad.- vantages of the present invention will be best appree ciated by reference. to the following detailed description of a presently preferred embod me when ta en in conjunction with the accompa yi g dr wing h ein:

Fig. l is an elevational view, with parts sectioned, show, ing an addressograph embodying features of the present invention;

Fig. 2 is a transverse sectional view, taken substan? tially along the line 2.--2 of Fig. l and looking in the direction of the arrows;

Fig. 3 is an enlarged fragmentary sectional view showing the details of coincidence detecting mechanisms arranged along the feed paths for the masters and blanks and in advance of the printing rollers; and,

Fig. 4 is a schematic diagram showing a presently preferred control and sensing circuit in accordance with the present invention.

Referring now specifically to the drawings, thereis shown in Figs. 1 and 2 an addressograph machine embodying features of the present invention which broadly includes a frame 10, cooperating printing rollers 12, 14, individual feed paths 1.6, 18 converging toward the printing rollers 12, 14 for delivering masters and impressionreceiving blanks to the rollers, and respective delivery mechanisms 20, 22 for initially disposing the masters and blanks along the feed paths 16, 18.

The cooperating printing rollers 12, 14 are respectively mounted on shafts 12a, 14a journaled by hearings on the frame 10. The uppermost roller 14 is preferably of a yieldable, hard rubber material to assure adequate peripheral contact with the lower roller 12 for printing superimposed masters and impressionareceiving blanks when delivered in face-to-face relation.

The master feeding mechanism 20, which delivers sue.- cessive masters M to the feed path or guide 16, may be of any conventional type, but preferably is pneumatically operated to assure positive pick-up of single masters. The details of the well known pneumatic delivery or feed mechanisms '20 are unimportant and for the present purposes it will sufiice to point out that the same includes an upwardly movable feed bag 24 carrying the stack of the masters M, and a rockable pneumatic pick-up head 26 which is supported on :a lever 28 and is arranged for compound movement from a broken-line pick-up posilaesseaa tion immediately over the stack of masters M, to the full-line drop-off position adjacent the feed path 16. Pneumatic pressure is derived through an inlet conduit 32 which is connected through to appropriate closed system 34 including a pump, an accumulator, and an electrically operable pressure on-off switch, all of well known construction. The switch, which may be electrically displaced to the OE position, is arranged such that pressure to the pick-up head 26 may be periodically interrupted to preclude lifting of successive masters although the head continues to rock between the full and broken line positions of Fig. 1.

v The feed path 16, receiving successive masters M from the pneumati c feeder 20, includes a pair of side-by-side conveyor belts 36a, 36b trained about an input roller 38. and about the lower printing roller 12, which is appropriately grooved. The input roller 38 is supported on a shaft 38a journaled by appropriate bearings on the frame and cooperates with a furtherinput roller 40 supported on a rotatable shaft 40a.

Hold-down finges 42a, 42b cooperate with the conveyer bands 36a, 36b to guide the advance of successive masters along the upwardly-inclined feed path from the feeder toward the printing roller 12, 14. Preferably, the hold-down fingers 42a, 4212 are elongated lengths of springy steel constrained at one end upon a cross bar 44 and arranged substantially coextensive with the feed path along opposite sides ofthe masters M. Cooperating with the hold-down fingers 42a, 42b and the conveyer bands 36a, 36b are lateral-confining guides 46a, 46b each in the form of an angle iron, which precludes side to side displacement of successive masters during feed along the path or guideway 16.

- The feeder 22 for delivering successive impression-receiving blanks B, such as cards or letters to be addressed, is of the mechanical type, such as the well known Pitney Bowes kicker type, and includes an electric drive motor 48 connected through an appropriate belt and pulley coupling to a sectoral kicker member 50 which extends through an elongated slot provided in a feed bed 52. The feed bed 52 carrie an adjustable prop 54 which maintains the impression-receiving blanks B in position for delivery to the blank feet path 18, appropriate resilient hold-down mechanisms 56 being associated with the kicker member 50. The mechanical feeder 22 operates in a well known manner and delivers successive blanks to the input end of the feed path 18 which is similar in all material respects to the feed path 16.

Briefly, the feed path 18 is formed side-by-side conveyer bands 58a, 58b extending over and beyond the grooved printing roller 12 and over an input roller 60 adjacent the feeder 22. The input roller 60 is supported on a rotatable shaft 60a and cooperates with a further input roller 62 likewise supported on a shaft 62a. Overlying the respective bands 58a, 581: are resilient holddown fingers 64a, 64b and cooperating with the superposed pairs of conveyer bands and hold-down fingers 58a, 64a, and 58b, 64b are the lateral-confining members 66a, 66b which may be adjustable, .as indicated by the arrows in Fig. 2, to accommodate blanks of various widths.

Adjacent the input end of the blank-feed path 18, there is arranged an appropriate mechanism for wetting the undersurface of successive blanks B being delivered to the feed path 18. The blank-wetting mechanism includes a wick or the like 68 in contact with input roller 60 which is gravity saturated from an overhead reservoir 70. Other systems for preparing the blank for the impression-transfer operation are contemplated.

A common electric drive is provided for the respective band-type conveyers 36a, 36b, and 58a, 5812 which is seen to include an electric drive motor 72 connected via an appropriate reduction gearing unit 74 and connecting belts 76, 78 to the grooved rollers 12, 60. Although the friction belt drive is connected directly to the roller 12 which serves a dual function, namely as part of both the conveying and printing systems, it is to be understood that the conveyer and printer may be independently driven.

The side by side conveyor bands, 58a, 58b of the blank-feed conveyer extend past the grooved printing roller 12 to a further roller 80. It will be appreciated that the stock of the blank B is somewhat wider than the masters M. Accordingly, the extension of the conveyer bands 58a, 58b to a location beyond the printing rollers 12, 14 forms a simple type duplex take-ofif. The wider blanks B may be separated from the masters M and removed by the continuation of the feed path 18 to a drop-off station, while the narrower stock may fall from the printing rollers 12, 14 directly into an appropriate collection bin or box 82.

As will subsequently be appreciated, the use of the upwardly feeding mechanisms 20 for the masters M, re-

' quires inversion of the successive blanks after the impression-transfer operation. For this purpose a deflecting member 84 is arranged at the take-01f location for the masters M and is disposed to flip the masters M over after leaving the printing rollers 12, 14 and prior to entering the collection bin 82.

As a prominent feature of the present invention, positive check and control means 86 are arranged at selected.

locations along the feed paths 16, 18 for sensing coincidence of a master M and an impression-receiving blank B at a relatively short throw or stroke from the print ing rollers 12, 14. The need for the coincidencedetecting station 86 in advance of the printing rollers 12, 14

will best be appreciated when it is recalled that direct.

graph equipment. A missed master or blank or piling of,

one master or blank upon another represent situations wherein there is an extreme risk that an account will not be serviced. The function of the coincidence-detecting station is to assure that a paired or tandem set consisting of a single master and a single blank are delivered to the printing rollers 12, 14. In addition, the coincidence-detection station serves to initially dispose the master in a required relation to prescribed areas of the impression-receiving blank. The desirability of this may be appreciated when it is recalled that impression transfer is often in a very limited area which is to be visible through a mailing envelope window or the like.

Although the mechanisms at the coincidence-detection station 86 are of an electro-mechanical nature, it is to be expressly understood at the outset that various detection systems are contemplated which are wholly mechanical, wholly electrical or electronic, or combinations there of. In the illustrative construction, respective single-pole, double throw microswitches 88, 90 are arranged along the feed path 16, 18 closely adjacent to printing rollers 12, 14. The respective microswitches are lifted and switched over from the position of Fig. 4 in response to contact with the leading ends of successive masters and blanks arriving at the coincidence-detection station 86.

Cooperating with the microswitches are respective steps- 92, 94 which are arranged in blocking relation to the masters and blanks moving along their respective paths. As seen in Fig. 2, the stops 92, 94 are in the form of fingers extending between the lateral-confining angle mem-" bers of the respective feed paths. The stops or blocking members 92, 94 are each pivotally mounted on brackets- 96, 98 and are connected to a common operating lever 100. It will be appreciated from an inspection of Fig. 3

short displacement will remove the stops from the feed path 16,18. The common operating lever or rod100 is connected to a push-type solenoid 102 of well known construction having an operating coil 102a and a movable plunger 102b biased in a direction opposite to the arrow by an appropriate spring 104. Upon energization of the solenoid 102 an upwardly directed force will be applied to the plunger causing an upward displacement of the rod 100 against the tension exerted by the spring 104. This movement is translated into the required displacement of the stops 92, 94 to bring same into a clearance position relative to the feed paths. Selective displacement of the operating means for the respective fingers 92, 94 is achieved through the provision of a control circuit which energizes the solenoid coil 102a only upon coincidence or pairing of successive masters and blanks. Upon inspecting Fig. 4, it will be seen that the circuit includes both microswitches 88, 90 connected in circuit with the operating coil 102a and in circuit with a suitable source of line potential or the like L1, L2. Closing of both the microswitches 88, 90 and energization of the solenoid coil 102a effects the required removal of the stop members 92, 94. As is well understood, the microswitches 88, 90, which are the sensing elements of the coincidence-detecting station, may be replaced by photocells, gaseous breakdown devices, or other suitable indicators.

As a further feature of the invention, the sensing elements are arranged in conjunction with appropriate relays and control switches to disable or interrupt feed of masters or blanks to the respective feed paths until sensing of successive pairings. For this purpose the controlling element for the pneumatic master feeder 20, designated by the numeral 186, is connected in circuit with the microswi tch 88 and across the line L1, L2. The control element 106 may be the electrical on-off switch controlling the suction valve of the pneumatic feeder, or as illustrated the motor drive for operating the arm 28. With the microswitch 88 in the position illustrated in Fig. 4, the control or actuating element 106 is energized, corresponding to normal operation and feed of the successive masters. When the circuit is interrupted, as by operation of the switch 88, the pneumatic pickup head 26 no longer rocks between the pick-up and drop-off positions, such that successive masters are not lifted. The required control over the delivery of masters is coordinated to the sensing and pairing of a master at the stop 92 by provision of a normally-open switch 108 and a control relay 110 energized in response to closing of the master-sensing element, namely the microswitch 88. The control relay, when energized, closes the normally-open switch 108. Similarly, the motor control 48 for the mechanical blank feeder 22 or a further control element, such as an electric clutch, is connected in circuit with a normally-open switch 112 and across the line L1, L2. The normally open switch 112 is closed by a relay 114 energized in response to closing of the blank-sensing element, namely the microswitch 90. Further switches, push buttons, and the like may be arranged in circuit with the various components to facilitate control, such as the main or master switch 116 across the line L1, L2, the auxiliary drive motor switch 118 in circuit with a speed control impedance 120 and the main drive motor 72, and the auxiliary switch 122 in circuit with the respective controls for the feeders 20, 22.

A typical operating cycle will now be described in detail:

Initially, the masters M are prepared by conventional hectograph-typing equipment from relatively bendable paper cards or the like. The hectograph impressions,

which occur on the operative face m of the masters M are a mirror image of the final impression to be received on the impression-receiving face b of the blanks B. The transfer operation is accomplished when the faces ni, b of the masters and blanks are brought into coextensive and facing relation. Since the master-feeder anism feeds downwardly, the masters are arranged withthe hectographed faces. m uppermost, and the blanksB.

are arranged with the impression-receiving faces b lower-- most. 1 a

Upon closing of the main and auxiliary switches 116, 118, 122, the drives and the respective feeders 20, 22 begin to deliver masters and blanks along respective feed paths. Specifically, a master delivery operationinvolves the displacement of the pneumatic pickup head 26 fromthe pick-up position wherein the uppermost master is lifted by suction and the rocking to the drop-off or release position wherein the 'driven input rollers 38, 40 causes the first master to be advanced along thefeed path 16. Linear displacement of the master along the path 16 is by frictional drive from the" band conveyers 36a, 36b arranged marginally of the master and .at a location calculated to preclude interference with the impression-transfer operation. Guiding of the masters along the prescribed linear path is assured through the provision of the lateral-confining elements 46a, 46b andthe appropriate gravity-engagedhold down fingers 42a, 42b. As to the delivery of the successive blanks B, energization of the motor 48 causes the kicker member 50 to deliver successive blanks B to thedriven input rollers. 60, 62 of the blank feed path 18. The surfaces of the lower input roller 60 are maintained in a wetted condition with an agent appropriate for the hectograph opera tion, such as alcohol, and contact the lowermost faces b of the successive blanks B. Linear displacement of the blanks B along the feed path '18 is through the friction drive of the band conveyers 58a, .58b. The feed rate for both themastersand blanks is controlled by the variable resistance in circuit with the con veyer drive motor 72. I

In the condition illustrated in Figs. .1 and 2. the leading blank B has reached the stop or blocking member 94- ahead of the corresponding master which is to be brought into tandem relation. Absent the coincidence-detection station 86, the blank and'master would not reach the, printing rollers 12, 14 in the required relation for transfer even though their respective paths of travel are sub-- stantially equal in length. This risk is greater, when it is recalled that a very definite and limited area of the. blank is to receive the impression, such as the portionwhich will subsequently become visible through the mail-.

ing window. The unprinted blank arrives at and closes the sensing or detecting element 90, to partially condition the electrically-controlled actuating means for the stop members 92, 94 which now preclude feed of the blanks and of the masters to the duplicating station.

Upon operation of the sensing'element'90, the drive 48 for the blank feeder 92 is momentarily interruptedand the blank feeder is brought to a momentary standstill awaiting the arrival of the master at the sensing or detecting element 88 along the feed path 16. The solenoid circuit is partially conditioned for fenergization by closing of switch 112 under control of relay 114. When the master operates its sensing element 88, the previously.

conditioned circuit for the solenoid coil 102a is completed by closing of switch 108'under. control of relay 110, and the stop members 92, 94 are removed from the feed paths 16, 18. Thereupon,v the paired master and.

blank are delivered through the relatively short stroke or throw to the printing rollers 12, 14 at which the hectograph portion of the uppermost face m of the master is brought into contact with the prescribed area of the wetted undersurface b of the blank B. The. impressiontransfer operation is followed by duplex takeoff and sep when the stack of masters M is ultimately built up-in the bin '82, it will be appreciated that it is. merely necesf sary to turnover thestack and oncev again the masters aeeaeaa 7 are in position for impressing their respective hectograph patterns on further blanks. After the tandem blank and master leave the coincidence-detecting station 86, it will be appreciated that the switches 108, 112 are once again restored to their normally-open position by deenergization of their respective relays 110, 114, and the microswitches 88, 90 return to the position of Fig. 4.

In the event that a master reaches the detection station 86 at a time in the cycle somewhat earlier than the delivery of a blank, the circuit for the delivery of successive masters will be first interrupted until such time as a blank arrives. Operation thereafter is substantially the same as described in conjunction with the early arrival of a blank.

It will be appreciated that the timing between the blank feeder mechanisms 22 and the master feeder mechanisms 20 is no longer of critical importance due to the interposition of the control and check system which is located in such proximity to the printing station to minimize the risk of non-registry between successive masters and'blanks. Further, the location of the respective stops from the printing rollers 12, 14 need not be the same, so that blanks of different lengths and usually longer than the masters, may be brought into the require longitudinal relationship with respect to the masters. That is, the trailing or leading portions of theblank may be readily formed with the impression by merely changing the location of the stops through suitable adjusting means, not shown.

Although the described arrangement shows a pneumatic system for the delivery of masters and a mechanical system for the delivery of blanks, it is to be understood that either or both of the delivery mechanisms may be of the mechanical or pneumatic type. From the standpoint of efficient operation and cost considerations, it has been found that the pneumatic delivery mechanisms for the masters makes the system somewhat more reliable.

While in accordance with the provisions of the statutes, we have illustrated and described the best form of embodiment of our invention now known to us, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus and method disclosed without departing from the spirit of our invention as set forth in the appended claims and that in some casm certain features of our invention may be used to advantage without a corresponding use of other features.

What we claim is:

1. In a machine for producing impressions from hectograph masters on work blanks, reproducing means for bringing paired masters and work blanks into hectographtransfer relation, individual feed paths for delivery of masters and work blanks to said reproducing means, coincidence'detecting means including sensing elements in, dividual to said feed paths, and means in operative relation'to said individual feed paths for precluding delivery of unpaired masters or blanks to said reproducing means and simultaneously removable from said feed paths upon sensing of coincidence.

2. A duplicating machine comprising reproducing rollers for bringing hectograph masters and impressionreceiving blanks into transfer relation, separate feed paths for said hectograph master and said blanks converging at said reproducing rollers, respective feeder means for delivering masters and blanks to said separate feed paths, a coincidence detector in advance of said reproducing rollers including means individual to said feed paths for sensing pairing of masters and blanks, removable blocking means along said feed paths for obstructing feed of unpaired masters and blanks to said reproducing rollers, operating means common to both blocking means for simultaneously removing same from the respective feed paths in response to sensing of a paired master and blank, and means individual to said feeder means and controlled from the corresponding sensing means of said coincidence detector for periodically interrupting feed of masters or blanks until sensing of a paired master and blank.

3. A duplicating machine comprising reproducing rollers for impressing hectograph masters against impression-receiving blanks, separate feed paths for said hectograph master and said blanks terminating at said reproducing rollers, respective feeder means for delivering masters and blanks to said separate feed paths, a

coincidence detector in advance of said reproducing rollers including microswitches individual to said feed paths for sensing pairing of masters and blanks, removable blocking fingers along said feed paths for obstructing feed of unpaired masters and blanks to said reproducing rollers, solenoid operating means for simultaneously removing said blocking fingers from the respective feed paths in response to sensing of a paired master and blank,.

and means individual to said feeder means and controlled.

, from the corresponding microswitch of said coincidence detector for periodically interrupting feed of masters or,

blanks until sensing of a paired master and blank.

4. A duplicating machine comprising reproducing rollers for bringing hectograph masters and impressionreceiving blanks into transfer relation, band-type conveyers forming separate feed paths for said hectograph master and said blanks arranged in superposed relation and converging at said reproducing rollers, respective feeder means for delivering masters and blanks to said conveyer for movement along said separate feed paths, a coincidence detector in advance of and adjacent said reproducing rollers including means individual to said feed paths for sensing pairing of masters and blanks, removable blocking means along said feed path following said coincidence detector for obstructing feed of unpaired masters and blanks to said reproducing rollers, operating means common to both blocking means for simultaneously removing same from the respective feed paths in response to sensing of a paired master and blank,

means individual to said feeder means and controlled from the corresponding means of said coincidence detector for periodically interrupting feed of masters or blanks until sensing of a paired master and blank, and a duplex takeoff following said reproducing rollers for separating said masters and processed blanks.

5. A duplicating machine for transferring a hectograph impression from a master to a mailing piece comprising transfer rollers, a first feed path for delivering masters to said rollers, a second feed path for delivering blanks to said rollers, master-feed means for said first feed path, blank-feed means for said second feed path operated in response to movement of a master past a predetermined location, master-sensing means along said first feed path, 1

blank-sensing means along said second feed path operated in response to movement of a blank past a predetermined location, movable blocking members along said first and second feed paths having a common actuating means, a coincidence detector in controlling relation to the actuating means of said blocking members and responsive only to operation of both said master-sensing means and said blank-sensing means, first disabling means in con-' trolling relation to said master-feed means and responsive to operation of said master-sensing means, and second disabling means in controlling relation to said blank-feed means and responsive to operation of said blank-sensing means.

6. A duplicating machine for transferring a hectograph impression from one face of a master to one face of a mailing piece comprising transfer rollers, an upwardlyinclined feed path for delivering masters to said rollers with said one face uppermost, a downwardly-inclined feed I path for delivering blanks to said rollers with said one face lowermost, master-feed means for said upwardly-' inclined feed path operated in response to movement of .a master past a predetermined location, blank-feed means for said downwardly-inclined feed path, master- Sensing means along said upwardly-inclined feed path operated in response to movement of a blank past a predetermined location, blank-sensing means along said downwardly-inclined feed path, movable blocking members along said feed paths having a common actuating means, a coincidence detector in controlling relation to the actuating means of said blocking members and responsive only to operation of both said master-sensing means and said blank-sensing means, first disabling means in controlling relation to said master feed means and responsive to operation of said master-sensing means, second disabling means in controlling relation to said blank-feed means and responsive to operation of said blank-sensing means, and a duplex takeofi? for said masters and blanks following said transfer rollers having means for inverting said masters.

7. In a duplicating machine including pressure rollers, first conveyer means for delivering successive masters to said pressure rollers, second conveyer means for delivering successive blanks to said pressure rollers, and a coincidence and feed control station at a location relatively close to said pressure rollers for assuring tandem delivery of successive masters and blanks to said pressure rollers, said station including respective sensing elements along said first and second conveyer means, respective stops along said first and second conveyer means in the paths of travel of said masters and blanks, a common electrically operated means for removing said stops simultaneously from the respective paths of travel, and a control circuit including first and second series-connected switches closed selectively by said first and second sensing elements for energizing said common electrically operated means whereby said stops are removed from the respective paths.

8. In a duplicating machine including pressure rollers, first conveyer means having an operating means for delivering successive masters to said pressure rollers, second conveyer means having an operating means for delivering Successive blanks to said pressure rollers, and a coincidence and feed control station at a location relatively close to said pressure rollers for assuring tandem delivery of successive masters and blanks to said pressure rollers, said station including respective sensing elements along said first and second conveyer means in controlling relation to the associated operating means, respective stops along said first and second conveyer means in the paths of travel of said masters and blanks, a common electrically operated means for removing said stops simultaneously from the respective paths of travel, and a control circuit including first and second series-connected switches closed selectively by said first and second sensing elements for energizing said common electrically operated means whereby said stops are removed from the respective paths.

9. A duplicating machine for transferring a hectograph impression from a master to a mailing piece comprising transfer rollers, belt conveyers providing a first feed path for delivering blanks to said rollers, master feed means for said first feed path having an electrically energized drive, blank feed means for said second feed path having an electrically energized drive, a master-sensing microswitch along said first feed path, a blank-sensing microswitch along said second feed path, removable blocking members along said first and second feed paths having a common solenoid control, a coincidence detector for energizing said solenoid control and responsive only to operation of both microswitches, said mastersensing microswitch being in controlling relation to the drive of said master feed means, and said blank-sensing microswitch being in controlling relation to the drive of said blank feed means.

10. A duplicating machine for transferring a hectograph impression from a master to a mailing piece comprising transfer rollers, a first feed path for delivering masters to said rollers, a second feed path for delivering blanks to said rollers, pneumatic master feed means for said first feed path, mechanical blank feed means for said second feed path, master-sensing means along said first feed path operated in response to movement of a master past a predetermined location, blank-sensing means along said second feed path operated in response to movement of a blank past a predetermined location, movable blocking means along said first and second feed paths having a common actuating means, a coincidence detector in controlling relation to the actuating means and responsive only to operation of both said mastersensing means and said blank-sensing means, first disabling means in controlling relation to said master feed means and responsive to operation of said master-sensing means, and second disabling means in controlling relation to said blank feed means and responsive to operation of said blank-sensing means.

11. A duplicating machine comprising reproducing rollers for bringing hectograph masters and impressionreceiving blanks into impression-transferring relation, separate feed paths for said hectograph master and said blanks converging at said reproducing rollers, respective feeder means for delivering masters and blanks to said separate feed paths, wetting means along the feed path for said blanks, a coincidence detector in advance of said reproducing rollers including switches individual to said feed paths for sensing the presence of masters and blanks, removable blocking fingers along said feed paths for obstructing feed of unpaired masters and blanks to said reproducing rollers, operating means common to both blocking fingers for simultaneously removing same from the respective feed paths in response to sensing of both a master and blank, and means individual to said feeder means and controlled from the corresponding switch of said coincidence detector for individually interrupting feed of masters or blanks until sensing of both a master and blank.

References Cited in the file of this patent UNITED STATES PATENTS 1,007,008 Roesen Oct. 24, 1911' 1, 53,824 Holmes Jan. 15, 1918 1,406,603 Belluche Feb. 14, 1922 2,384,768 Rau Sept. 11, 1945 2,395,740 Hileman et a1 Feb. 26, 1946 2,572,450 Crissy Oct. 23, 1951 2,617,647 Davis Nov. 11, 1952 2,744,562 La Rocca et a1 May 8, 1956 FOREIGN PATENTS 562,507 Germany Oct. 26, 1932 

